1. Field of the Invention
The present invention relates broadly to homogenization of molten glass in a continuous glass melting furnace, and more particularly to improved drive means for stirrers employed in such homogenization. 2. Description of the Prior Art
Various forms of stirrers have been employed for some time in continuous glass melting furnaces in order to improve the homogeneity of the molten mass. U.S. Pat. No. 3,236,618, for example, suggests the use of counterrotating intermeshing paddles immersed in the stream of molten glass, while U.S. Pat. No. 3,350,187 suggests the use of one or more rows of screw-type agitators or propellers extending across the stream for setting up vertical currents to intermix the molten mass.
More recently, for purposes of further improving homogenization as illustrated by U.S. Pat. Nos. 3,997,315 and 4,046,546, glass melting tanks have been constructed with relatively narrow sections or waists through which the glass flows from the melting and refining areas to the conditioning zone. The stirrers are located in a line across this waisted area and rotated about their vertical axes so as to, in combination with the flow characteristics created by the tank construction, significantly improve the homogeneity of the molten glass delivered to the working area of the facility.
Conventionally, in order to permit synchronized operation of the stirrers and allow the power source to be located away from the intense heat of the waist area, they have been driven as by connection to a line shaft operated by a common power source such as a hydraulic or electric motor. The aforementioned U.S. Pat. Nos. 3,350,187, 3,997,315 and 4,046,546, for example, illustrate schematically such drive systems. While such drive trains provide synchronization of both speed and relative angular position of the individual stirrers, they do present certain limitations.
Thus, it occasionally becomes necessary to remove and replace one of the individual stirrers. To accomplish this, it is necessary to discontinue operation of the entire group of stirrers while the faulty unit is replaced. Changing the relative speed, direction of rotation or relative angular position of individual stirrers likewise requires disruption of the entire stirring process. Should a malfunction occur anywhere in the drive train, all of the stirrers will discontinue operation. In spite of the inherent limitations, it was previously deemed of sufficient importance for the stirrers to be synchronized and the power source to be in a less hostile environment that the heavy, cumbersome common drive was employed.